Etch process and apparatus therefor
US6699400B1 · kind B1 · utility
Inventors
Key dates
| Filing date | Jun 4, 1999 |
| Grant date | Mar 2, 2004 |
| Priority date | — |
| Expiry date | Jun 4, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S134/902
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
In a process using a hot phosphoric acid etchant (12) to etch silicon nitride on a semiconductor wafer (15) submerged in a tank (11) of the etchant (12), a recirculating path is established for the etchant (12). A porous filter (35) is coated with silicon nitride and installed in the recirculating path. As the etchant (12) in the recirculating path flows through the porous filter (35), the silicon nitride on the porous filter (35) dissolves into the etchant (12). In the tank (11), the silicon nitride dissolved in the etchant (12) significantly suppresses the etch of silicon dioxide on the semiconductor wafer (15), thereby enhancing the etch selectivity of the process. Monitoring and maintaining the concentration of the silicon nitride in the etchant (12) stabilizes the etch selectivity of the process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.